Audible alarm for telephone systems



Nov. 4, 1952 S, SLEZAK 2,616,979

AUDIBLE ALARM FOR TELEPHONE SYSTEMS 'PA/Qa OFF/cfs FLOOR B TONE Y BAR WVU/TOR 5. Z' 5L [ZAK A7' 7' ORNE V Nov. 4, 1952 Filed March 17. 1949 FIG. 2

S. T. SLEZAK AUDIBLE ALARM FOR TELEPHONE SYSTEMS 2 SHEETS-SHEET 2 /M/wron 5. 7. SLEZAK ATT ORNE V Patented Nov. 4, 1952 UNITED staresN ATENT OFFICE AUDIBLE ALARM FOR TELEPHONE SYSTEMS Stanley T. Slezak, Flushing, N. Y., assignor `to l Bell Telephone Laboratories, Incorporated, New

York, N. Y., a corporation of New York Application March 17, 1949, Serial No. 81,969

Claims. 1

. trouble conditions occurs and this apparatus' is arranged to give minor alarms or major alarms depending on the nature and seriousness of the trouble. This miscellaneous alarm apparatus includes bo-th visual and audible signals. The audible signals may include buzzers or bells and may include a tone bar which is repeatedly sounded while a majoralarm condition exists. The visual signals include oor lamps, aisle pilot lamps and' frame lamps to aid the maintenance man in locating the trouble which is causing the alarm; :and the alarm signals terminate when the trouble is cleared.

When a plurality of ltypes of office equipments are provided, the maintenance force is usuallyV divided into groups, each group familiar with, and skilled inclearing trouble conditions in, a particular type of equipment. At times When thereA are maintenance men on duty for each type of equipment and for each oor of oiiice equipment of the same type, the trouble alarm signalfmay be given only on the floor or area in which the particular oice equipment or type of equipment is located. At other times, the entiremaintenance force'may be stationed .at one of' thealarm locations, for instance when there is only one man for each type of equipmentvor ay singleman for" all equipments; and, in such a case,- it is desirable that ,alarms forl all types of equipments begiven at all alarm apparatus locations.

This invention isa'system' of trouble alarm signaling particularly adapted for use in telephone olce buildings Whichhouse differentltypes of equipmentand different members of the maintenance' force areassigned to maintain each different'kind oiequipment. `According to the inventionpa tone bar 'andi code bell and a code alarm'circuit`.are`provided'at each o-f a plural- Y ity offlo'cations inta' building housing telephone. oiiicel equipment for igivin'glanlaudble alarm .indicative of-tli'etypefA of equipment with'whicnthe' 2 1 alarm circuit is associatedwhen a troubletalarm condition exists therein, and for repeatingthe signal at intervals until the trouble condition is cleared. A .feature of.u the invention is anarrangement whereby the trouble alarm apparatus associated with each different type ,of telephone oice equipment and with each location ofth'e.

same type of equipment may be switchedltogether; so thatr a trouble alarm code will be sounded at all of the alarm apparatus locations whenever a ktrouble condition exists in `the. cor- .responding type of equipment, the codes forall .types of equipment in which trouble conditions simultaneously exist beingsoundedin successionlv and vcyclically repeated at predeterminedinter types or number of types shownin the drawing. but is generally applicable toY any signaling sys-l tem involving selectiveV coded supervisory signaling.

Referring to the drawings:

Figs. 1a, 11),.10 and 1d show an audible alarm signaling .system associated with telephone oiiice equipment, the. alarmgapparatus of Fig. 1a being associated with `one Aor more cross-bar office units,

the-alarm.apparatus of Figs. 1b and L1c beingv .associated with paneloiiioeequipments, and the alarmapparatusofF-ig. ldbeing associated with tolllofceequipment; and

Fig. 2- shows indetail the alarm Acode circuit which is included in the alarm apparatus of each,

of Figs. 1a, 1b, lc andld.

The alarm system shown in the drawing is arranged for three different alarm'codes, code I for the cross-bar oflice equipment, code 2ii`or the panel oince equipments and code -3 forthe toll oiiice equipment.

provided for each floor. Alarm apparatus for each equipment includes the usual alarmrelaysf which` are operatedwhen amajor trouble condition arises, `these relays being represented in Fig;

la by relays Il and l2, in-Fig. 1b by relays 2l and 22, in Fig. 1c by relays V3| and 32 and in Fig.

1d by .relays 4I and 42. Reference may Vbe-had` to the patent to J. N.:Walters. 2,262,595 granted; November l1, .19.41, fora general description, of. miscellaneous. alarmA equipment usuallyprovided Since panel equipments are e shown on two floors, ythere is an alarm apparatus in a telephone oice of the step-by-step type. In addition to the usual alarm apparatus represented by the relays II, 2|, 3l and 4I, there is provided for each of the cross-bar, panel and toll equipments, a code circuit It), 25, 33 or 33, a tone bar I8, 28, 38 or 38 and a code bell E3, 29, 33 or Q9. Each of the code circuits IB, 25, 35 and 53 is similar, and one such code circuit is shown in detail in Fig. 2. Each of the code circuits i3, 28, 33 and i0 has associated therewith an interrupter Ill, 2:1, 3d or 33 and a control relay I3, 23, 33 or i3 which is controlled by the alarm relays of the associated equipment. The tone bars I3, 23, 33 and 3S, one for each of the four equipments, may be a part of the regular miscellaneous alarm equipment provided for giving audible alarms. Each code bell is a direct-current controlled bell cf the single stroke type and the various alarm codes for the diierent types of equipment constitute'a stroke on the tone bar followed by either one stroke, two strokes or three strokes on the code bell. A key 35 and alarm switching relay 3S are provided in the alarm apparatus associated with the panel oilce equipment on floor B for switching the code circuit 33 into connection with the code circuit 20 of the alarm apparatus associated with the panel equipment on oor A; whereby a trouble condition in the panel equipment of either oor will cause the alarm code for panel equipment to be sounded on both floors. A like key I5 and switching relay I5 is associated with the alarm apparatus for the cross-bar equipment, and a key 45 and switching relay B3 is associated with the toll oce equipment; whereby the code circuits IEI and D may likewise be connected with code circuit 2Q in order that all alarm codes for all the different types of equipment will be sounded by the tone bar and code bell associated with alarm apparatus of each of the diierent equipments as hereinafter described in detail.

The alarm code circuit shown in Fig. 2 comprises a group of relays 6I to 68 which are cylicaln ly operated to repeatedly sound one or more of the alarm codes depending upon the type or types of equipment in which a trouble condition exists and a set of two relays for each diierent type of equipment, relays 'Ii and l2 for the cross-bar office equipment, relays 8i and 32 for the panel office equipments and relays 3l and 92 for the toll oice equipment.

Assume now that a trouble condition occurs in the cross-bar olce equipment which causes the operation of one or the other or both of relays Il and i2 of the miscellaneous alarm apparatus. The operation of relay II or I2 closes a circuit for operating relay I3; and the operation of relay i3 connects ground to each of conductors 53 and 54 of code circuit I3. The associated inter rupter lll is of the continuously operating reciproeating type which alternately connects conductor 53 to each of conductors 5I and 52 once every half second. As soon after the operation of relay I3 as interrupter Iii next connects ground to conductor 52, a circuit is closed through a back contact of each of relays 68, 33, SIB and 62 in the order named for operatively energizing the winding of relay 6I of code circuit I3. Relay I relay 'I2 for operatively energizing the Winding of relay TI. Relay 'II locks through a back contact of relay 72 to the grounded conductor 53 and connects ground to conductor T3. As soon after relay 3l operates as interrupter I4 connects ground to conductor 5I, a circuit which includes a back contact of each of relays 3l', G5 and 63 andV a front contact of relay 6l is closed for operatively energizing the winding of relay 62. Relay 62 locks through a back contact of relay 64 to conductor 53; connects ground to conductor 58, to which ground is already connected at a front contact of relay 8 I; and connects the winding of relay 33 through back contacts of relays 34, 56 and 33 to conductor 52. When interrupter I4 next connects ground to conductor 52, relay 63 operates and is locked operated through a back contact of relay 65 to conductor 53. The operation of relay 33 opens the locking circuit of relay 6I and connects the winding of relay Se through back contacts of relays 55 and 61 to conductor 5I. Relay 3i releases; and, when interrupter I next connects ground to conductor 5|, relay 34 operates and is locked operated through a back contact of relay 35 to conductor 53. The operation of relay G4 opens the locking circuit of relay 52 and connects the winding of relay 35 through back contacts of relays 65 and 53 to conductor 52. Relay 62 releases thereby causing the deenergization of the tone bar I8; and when interrupter I4 next connects ground to conductor 52, relay 65 operates and is locked operated through a back contact of relay 5l to conductor 53. The operation of relay 35 opens the locking circuit of relay 33; connects the winding of relay 36 through a back contact of relay 31 to conductor 5I; and closes a circuit from grounded conductor 73 through a back Contact of relay 66, a front contact of relay E5 and conductor 59 for operatively energizing the code bell I8, whereby there is one stroke cf the code bell to indicate that the trouble which caused the preceding operation of the tone bar is a trouble in the cross-bar equipment. Relay 3S releases; and, when interrupter i5 next connects ground to conductor 5I, relay 63 operates and is locked operated through a back contact of relay 3S to conductor 63. The operation of relay 35 opens the locking circuit of relay 34; opens the connection between conductors 'I3 and 59, there by deenergizing the code bell I8; and connects the winding of relay Bl', through a back contact of relay 63, to conductor 52. Relay Scl releases; and, when the interrupter I3 next connects ground to conductor 52, relay 61 operates and is locked through a back contact of relay 6i to conductor 53. The operation of relay ST opens the locking circuit of relay 65; connects the winding of relay 68 to conductor 5i; and closes a circuit which includes a back contact of relay 68, conductor 39 and a front contact of relay 1I for operatively energizing the winding of relay i2. Relay 65 releases, and relay i2 operates and is locked operated through a front contact of relay 'FI and a back contact of relay 92 to conductor 53. The operation of relay 12 opens both the aforementioned operating and locking circuits of relay II but closes another locking circuit for relay 'II through conductor E9 until relay 68 is operated. When interrupter I4 next connects ground to conductor 5I, relay 68 operates and is locked operated through a back contact of relay G2 to conductor 53. The operation of relay 68 causes the release of relays 66 and 'Il and connects the winding of relay 6| andere.

to. conductor 52'. The release of relay 1I: causesthefrelease of relayf 12, thus ending onecyclefof the operation of relays 5I to 58. Thev release ofrelaysll and 'IZ prepares for a recheck of the existenceof a trouble conditiomas..evidencedV by ground potential on conductor 54. As soon thereafter as interrupter le again connects groundl to conductor 52, relay 5l reoperatesrbeginningla new cycle of operation of relays'l to 68. r-Ilhe reoper-ation of relay 5! causes the release of relay" El, reconnects the winding of relay 62 to conductor 5l, connects ground to conductor 58 to cause another stroke. onthe'. tone bar I8, and:A again closes. the circuit for. operating relay 'H When.. interruptor l5? next. connectswground to conductor 5l, relay 52 is vreoperatedand'l locked to-.xc'onductor 53.` and relay Sais released.` `The second cycle of` operation of relays 6I to @Sis completed inY the-manner hereinbefore described; and theserelays continue to be. operated and releasedy in .the above-describedv order and. manner4 to cyclically: cause one strokey on the tone. bar. l5. followed by one stroke. on. the code bell Hl until the trouble is cleared whereupon. the operated miscellaneous alarm relay Il releases followed by the release of relay I3. When relay I3 releases, ground is disconnected from conductors 53 and '55 and all ofthe relays in the code' circuit ii! are restored to normal.

When a trouble condition arises in the panel equipment onoor A, the operation of a miscellaneous alarm relay 2i or 22 causes the operation of relay 23; and the operation cf relay 23 connects ground to conductors 53 and 55 of `code circuit, 25, thereby causing the relays 5t to 58 of this code circuit to operate in the manner above described for code circuit i5. Since. ground is connected to conductor 55 instead. of to conductor 54, relay 8l is operated instead of relay 7l; and the operation of relay 8i connects ground through a back contact ofi relay 7i. to conductor B3. Whenrelay 5I operates, it causes one stroke on the tone bar 28;; when relay 53 operates it causesa rst stroke of the code.y bell 29, and when relay 55 operates it' causes a secondstrolv on the code bell 29. When relay 5l operates, relay' 82 is'operated; and, at the end of the cycle of operation of relays 5l to 58, relays 5I and 82 are'released to enable av checkof the continued existence of trouble on floor A when relay 5l reoperates. The alarm code consisting of a stroke onv the tone bar 28 followed by two strokes on the code bell 29 continues to be sounded until the trouble on floor A has been cleared' and relays 2l, 22 and 23 are' released.

When a trouble condition arises in the panel equipment on door B, the operation. of the. alarm relay'i or 32 causes the operation of relay; and. the operation of relay 33 connects ground to conductors 53 and 55 of code circuit' 35 which thereupon operates in identical manner to that in which code circuit 2E! is operated as aboveV described to' cyclically sound the tone bar 38 followed by two strokes on the code bell 3S. If the key 35 is operated, rela-y 3e operates' to individually connect each offconductors 53, 5d., 55j and' 55 of code circuit-35 to the corresponding conductors of code circuit 2i); so'that both of these'code circuits will be operated responsive toa trouble condition on-either or both of floors A and B to sound the audible alarm and' code for-'panel equipment on both oors, the usual oor pilot lamps (not shown) being effective tol inform4 the maintenance manV whether' al trouble# 75 condition exists on iioor A or o'or'B or onboth floors.` When the troublehas been cleared and" relays4 23 and 53 have bothrreleased, the code circuits 20 and 3! are restored to normal.

When. atrouble condition occurs in the toll cnice equipment, an alarm relay 5l or 42 causes the operation of relay 53; and the operation of relay. i3 connects ground to conductors 53 and 55, thereby causing the operation of code relays @i tote of code circuit i5 in the manner above described for code circuit i5. Since ground is connected tc conductor 55 instead of conductor relay El is operated instead of relay 1I; and-the operation of relay 5l connects ground to conductor 53, causesionestroke on the tone barfli; whenrelay 53 operates it causes a firstA stroke of the; code.' bell 55; when relay 55 operates it causes a second. stroke' of the. code bell 59; and when relay 6.1. operatesV it causes a third stroke of thev code.

bell 45 and causes the operation of relay 92.

At. 'the end of the cycle of operations of relays' 5i to 55, relays 5i and 92 are released, to enable. a check ofthe continued existence of. trouble in the toll= oiiice equipment when relay 5I. reoperates.. The alarm code consisting of a stroke cn thel tone bar 53 followed by three strokes of the tone bar i9 continues to` be sounded until the trouble in the toll office equipment has been cleared and relays lil, i2 and 53 are released.

Assume now that keys l5, 55 and i5 have all been operated in order that all major alarm signals will be given Ain all alarm locations. Relays l', 55 and 55 operate to interconnect the corresponding conductors 53, 55, 55 and 56 of code circuits iii, '25, Sil and 55. Whenever a troublel condition-occurs in one or more of the four equipments, one or more of relays I3, 23, 33

and 53 are operated, thereby connecting ground to conductor 55 of all four code circuits and` connecting ground to each of conductors 55, 55'

and 5S of all four code circuits which identifies the type of equipment in which trouble exists. 1f relay Yl5 alone is operated, all of the code circuits operate as above described for code circuit iii4 to sound the alarm code for cross-bar equipment on all tone bars and code bells; if relay 25 or is operated or if both of these relaysare operated, all of the code circuits operate as above described to sound the alarm code for panel equipment on all tone bars and code bells; and if relay 53 alone is operated, all of the code circuits operate to sound the alarm code .for toll office equipment on all tone bars and code bells. If a trouble exists in more than one of the different' types of equipment at one time, all of the code circuits are operated to sound in sequence the corresponding alarm codes identifying the types of equipment in which trouble exists; and as soon as the trouble` is cleared in a particular type of equipment to terminate'the sounding of the corresponding code but continue the cyclic sounding of the other codes corresponding to types of equipment in which troubles continues to exist. If, for instance, relays i3, 25 and 43 are operated, the operation cf each of the code circuits til, 25, 35 and #is will be similar except that each is controlled by its own interruptor it, 25, 35 or 54. Theoperations of code circuit i5 at such'a time will be described. With ground connectedV to conductors 53, 5ft, 55 and 55, the next connection of' ground to conductor 52 by interrupter is causes the operation of relay 5l. The operation' of relay ilwcauses a stroke on thetone bar When relay 5i operates,v it.

I8 and closes circuits for operating each of relays 8| and 9|. The operation of relay 65 connects ground to conductor 59 to cause one stroke on code bell I9; but since relay operated, the operation of each of relays G3 and 61 does not connect ground to conductor 59, so that the first code sounded is the alarm code for trouble in the cross-bar oice equipment, The operation of relays 6! connects ground to conductor S9, operating relay l2. Relay 'l2 locks through front contacts of relays 7|, 8| and 9| in parallel and a back contact of relay 92 to conductor 53. When relay 68 operates, relay H releases but relays "l2, 9| and 9| remain operated, being locked to conductor 53, and when relay 6| reoperates to begin a second cycle of the operation of relays 6| to 68, relay 1| cannot reoperate. rl'he second cycle operation of relay 6| causes a stroke on tone bar i8; the operation of relay e3 causes a irst stroke on code bell E9 and the operation of relay i causes a second stroke on code bell ES; but, with relay 8| voperated, the operation of relay does not connect ground to conductor 59 so that the alarm code sounded on the second cycle of operation of relays Bi to 68 is the alarm code for trouble in the panel equipment. The second cycle operation of relay 6l connects ground to conductor E9, operating relay S2; and relay 82 locks through front contacts of relays 8| and 9| and a back contact of relay 92 to conductor 53. When relay BS operates, relay Si releases but relays 52, 82 and 9| remain operated, being locked to conductor 53, and when relay 6| reoperates to begin a third cycle or the operation of relays 5| to 98, neither of relays 7| or 8| can reoperate. The third cycle operation of relay 6| causes a stroke on the tone bar i3, the operation of relay 63 causes a rst stroke on code bell |9, the operation of relay 65 causes a second stroke on code bell I9, and the operation of relay E57 causes a third stroke on code bell |55 thus sounding the alarm code for trouble in the toll oice equipment. The third cycle operation of relay 61 also causes the operation of relay 92. When relay 68 operates, relay 9| releases; and the release of relay 9| causes the release of each of relays l2, 82 and 92. The code circuit is now normal, ready to begin a new cycle of operations and ready to check the condition of the diierent types of equipment to determine which codes are to be again sounded in rotation.

Assume now that when relay 6| reoperates, the trouble condition in the panel equipment has been cleared and relays 23 and 33 are both normal but that trouble continues to exist in the cross-bar and toll omce equipment. In this event, the operation of relay 6| causes the reoperation or" relays 'il and 9|; and the alarm code for the cross-bar equipment is sounded by the rst cycle of operation of relays 5| to E8. The operation of relay 'i, causes the operation of relay l2; and the operation of relay 68 4causes the release of relay 7|. Relays 'l2 and Si remain operated and on the next cycle of operations, the alarm code for the toll office equipment is sounded; the operation or" relay 6l causes the operation of relay 92, the operation of relay S2 causes the release of relays l2 and 9|; and the release of relay 9| causes the release of relay 92.

From the foregoing it is apparent that each time that all of relays 1|, 8| and 9| are released, a check is made of the condition of the different types of equipment to determine which codes are to 'be sounded in rotation by the operation of relays 6| to 68; and when all troubles have been cleared, none of relays I3, 23, 33 and 43 will be operated and the cyclic operation of each of the interconnected code circuits I0, 2|), 3) and 40 will cease.

Each of switching relays I6, 35 and 4S controls a oor lamp Il, 3l and 4l respectively for giving a visual indication that the code circuit of that equipment is combined With the code circuit 29 at the alarm center, which in the arrangement is on floor A.

What is claimed is:

1. In combination, a plurality of telephone switchboards, a plurality of alarm units, one for each switchboard, a plurality of alarm codes, a ditferent code for each switchboard, audible alarm means for each alarm unit, control means in each of said alarm units comprising a series of relays operable to sound the alarm code of the switchboard to which the unit is individual while an alarm condition exists therein, and relay switching means for interconnecting the control means of all of said units thereby to eiect the operation of all units to sound in succession the alarm code for each switchboard in which a trouble condition exists.

2. In combination, a plurality of telephone switchboards, a plurality of alarm units, one for each switchboard, a plurality of alarm codes, a different code for each switchboard, means in each of said alarm units comprising a series of relays operable to eiect the sounding of any one or said alarm codes or the sounding of a plurality of said codes in succession, circuit control means individual to each of said alarm units for causing the operation of the unit to repeatedly sound the alarm code of the switchboard to which the unit is individual while a trouble condition exists therein, and means comprising a relay for interconnecting the control means of two of said alarm units thereby to operate both alarm units to repeatedly-sound either one or both of the alarm codes in succession depending upon whether an alarm condition exists in the one or the other or bot-h of the switchboards to which said two alarm units are individual.

3. In combination, a plurality of different types of switchboard equipment, alarm relays and alarm codes, a relay and a diierent alarm code for each type of equipment, and alarm apparatus individual to each equipment controlled by the alarm relay individual thereto, each alarm apparatus comprising a code bell, a tone bar, an interrupter, a series of relays operable in succession under the control of said interrupter for energizing said bell and tone bar, and a set of control relays corresponding to each type of switchboard equipment for rendering the operation of any one of said alarm relays and said series of relays effective to energize said bell and tone bar to sound the alarm code corresponding to the equipment to which the operated alarm relay is individual, each of said different codes consisting of one stroke of the tone bar followed by one or more strokes of the code bell.

4. In combination, a plurality of different types of switchboard equipment, alarm relays and alarm codes one of each for each type of equipment, alarm apparatus individual to each equipment controlled by the alarm relay individual thereto, each alarm apparatus comprising a code bell, a tone bar, an interrupter, a series of relays operable in succession under the control of said interrupter for energizing said |bel1 and tone bar,`

and a set-:cfeontrol relays corresponding to each type-ofgswitchboard equipment for rendering the loperation of any one of saidalarm -relays'andfsaid series of Lrelays eifective to energize saidvgbell rand Atone bar ,tez-sound the alarm code` corresponding -to `the equipment to Whichfthewoperated alarm relayis individual, eacnlof `saiddiiferent codes apparatus :of a particular equipment responsive fonly to the operation of` the-alarm relay individual to ,l saidv particular equipment.

`5. Incombination, a pluralityofgdiierenttypes of equipment, a plurality of alarm relays, each of said relays individual to a diierent type of equipment and each relay operated responsive to the existence of a trouble condition in the equipment to which the relay is individual and an alarm apparatus unit for sounding dierent alarm codes, a different code for each type of equipment, said alarm apparatus unit comprising an electromagnetically actuated tone bar, an electromagnetically actuated bell, an interrupter, a series of alarm coding relays operable in succession under the control of said interrupter while any one of said alarm relays is operated, and a set of code control relays for each different type of equipment, each said set operated Whenever the alarm relay for the same type of equipment is operated for rendering the operation ofl said series of coding relays eiective to operate said tone bar and bell to sound the alarm code which identies any equipment the alarm relay of which is operated.

6. In combination, a plurality of different types of equipment, a plurality of alarm relays, each of said relays individual to a different type or equipment and each relay operated responsive to the existence of a trouble condition in the equipment to which the relay is individual and an alarm apparatus unit for sounding diierent alarm codes, a different code for each type of equipment, said alarm apparatus unit comprising an electromagnetically actuated tone bar, an electromagnetically actuated bell, an interrupter, a series of alarm coding relays operable in succession under the control of said interrupter While any one of said alarm relays is operated, and a series of sets of control relays, one set for each different type of equipment, each set comprising a first relay `operated Whenever the alarm relay of the same equipment is operated for conditioning said series of alarm coding relays for sounding the particular alarm code which identies the equipment, and a second relay operated when the complete alarm code has been sounded for preventing the re sounding of the same code until the correspond-- ing alarm code has been sounded for each of the other equipments the alarm relay of which is operated.

7. In combination, a plurality of diferent types of equipment, a plurality of alarm relays, each of said relays individual to a different type of equipment and each relay operatedv responsive to the existence of a trouble condition in the equipment to which the relay is individual and an alarm apparatus unit for sounding different alarm codes, a diierent code for each type of equipment, said alarm apparatus unit comprising an electromagnetically actuated tone bar, an electromagnetically actuated bell, an interrupter, a series of alarm coding relays for operating said tone bar and bell to sound any one of the alarm codes or a plurality of said alarm codes depending upon kwhether one `or more of Asaid alarm relays is operated, meansvcomprising said interrupter for cyclically operating said alarm coding relaysinsuccession, a series of sets'of control relays, `one set for each different type of equipment, a first control relay of each set being roperated Whenever the alarm relay of the same equipment is operated, means comprising a iirst one of said alarm coding relays for actuatingsaid toneibar atthelbeginning ofeach cycle of operation of-said alarm :coding relays,.and meanscomfprising-said first relay of each set ofcontrol re.- lays andsaidalarm coding relays for selectively actuating said bell onev ormore times following theactuatiOn ofsaid-tone bar to identify in succession each equipment the alarm relay of which is operated.

Y i8. Ifnlcembination a: plurality; of f dierntftypes of equipment, a like pluralityoff-different alarm codes, a plurality of alarm relays, each of said relays individual to a different type of equipment and each relay being operated responsive to the existence of a trouble condition in the equipment to which the relay is individual, and alarm apparatus units each individual to a different one of said alarm relays, each alarm apparatus unit comprising an electromagnetically actuated tone bar and an electromagnetically actuated code bell and a variably operable alarm coding relay unit, the operation of each of the alarm relays being effective to control the operation of the alarm coding unit of the alarm apparatus unit which is individual to the operated alarm relay to sound the corresponding one of said plurality of different alarm codes, each alarm code consisting of a stroke on the tone bar followed by one or more strokes on the code bell.

9. In combination, a plurality of diierent types of equipment, a like plurality of different alarm codes, a plurality of alarm relays, each of said relays individual to a different type of equipment and each relay being operated responsive to the existence of a trouble condition in the equipment to which the relay is individual, alarm apparatus ,Y units each individual to a different one of said alarm relays, each alarm apparatus unit comprising an electromagnetically actuated tone bar and an electromagnetically actuated code bell and a variably operable alarm coding relay unit, the operation of each of the alarm relays being effective to control the operation of the alarm coding unit of the alarm apparatus unit which is individual to the operated alarm relay to sound the corresponding one of said plurality of diierent alarm codes, each alarm code consisting of a stroke on the tone bar followed by one or more strokes on the code bell, and switching means for connecting a particular one of said alarm coding units to another one of said alarm coding units, whereby both units are rendered operatively responsive to the existence of a trouble condition in each of two types of equipment.

l0. In combination, a plurality of different types of equipment, a like plurality of different alarm codes, a plurality of alarm relays, each of said relays individual to a diierent type of equipment and each relay being operated responsive to the existence of a trouble condition in the equipment to which the relay is individual, alarm apparatus units each individual to a different one of said alarm relays, each alarm apparatus unit comprising an electromagnetically actuated tone bar and xan electromagnetically actuated code bell and a variably operable alarm coding relay unit, the operation of each of the alarm relays being eiective to control the operation of the alarm coding unit of the alarm apparatus unit which is individual to the operated alarm relay to sound the corresponding one of said plurality of different alarm codes, each alarm code consisting of a stroke on the tone bar followed by one or more strokes on the code bell, and switching means for individually connecting a particular one of said alarm coding units to each of the other alarm coding units, whereby all of said coding units are rendered operatively responsive to all of said alarm relays which are simultaneously held operated responsive to a trouble condition in the equipment to which it is individual.

STANLEY T. SLEZAK.

REFERENCES CITED The following references are of record in the le'of this patent:

Number 12 UNITED STATES PATENTS Name Date Beach et al Dec. 2, 1913 Clausen Apr. 20, 1920 Powell Jan. 12, 1926 Friendly May 10, 1927 Saunders Feb. 28, 1933 Hatton June 6, 1933 Harrington Mar. 6, 1934 Walters Nov. 11, 1941 Dimond Mar. 31, 1942 Wallace Nov. 18, 1942 Priessman Nov. 14, 1944 Schneckloth Mar. 20, 1945 

